A major challenge in engine oil formulation is simultaneously achieving wear control, while also achieving friction reduction, deposit control and/or oxidation stability, over a broad temperature range.
Lubricant-related wear control is highly desirable due to increasing use of low viscosity engine oils. As governmental regulations for carbon emissions become more stringent, use of low viscosity engine oils to meet the regulatory standards is becoming more prevalent. At the same time, lubricants need to provide a substantial level of durability and wear protection due to the formation of thinner lubricant films during engine operation. As such, use of antiwear additives in a lubricant formulation is the typical method for achieving wear control and durability. Due to limitations of using high levels of sulfur-containing and phosphorus-containing antiwear additives such as catalyst poisoning, it is highly desirable to find alternative methods for achieving excellent wear control and durability without poisoning the catalyst.
Most current antiwear additives contain phosphorous and/or sulfur. Zinc dialkyl dithiophosphate (ZDDP) is a common antiwear additive used in engine lubricants. However, these elements are known to harm catalysts used to treat exhaust gases from internal combustion engines, and thus antiwear additives which are free of sulfur and phosphorous will be advantaged in the marketplace.
Despite advances in lubricant oil formulation technology, there exists a need for an engine oil lubricant that effectively improves wear control while maintaining or improving friction reduction, deposit control and/or oxidation stability.